The Experts below are selected from a list of 1596 Experts worldwide ranked by ideXlab platform
Mario Huesca - One of the best experts on this subject based on the ideXlab platform.
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enterohemorrhagic escherichia coli induces apoptosis which augments bacterial binding and phosphatidylethanolamine exposure on the plasma membrane outer leaflet
Infection and Immunity, 2000Co-Authors: Debora Barnett Foster, Maan Abulmilh, Mario HuescaAbstract:Enterohemorrhagic Escherichia coli (EHEC) is a gastrointestinal pathogen that causes watery diarrhea and hemorrhagic colitis and can lead to serious and even fatal complications such as hemolytic uremic syndrome. We investigated the ability of EHEC to kill host cells using three human epithelial cell lines. Analysis of phosphatidylserine expression, internucleosomal cleavage of host cell DNA and morphological changes detected by electron microscopy changes revealed evidence of apoptotic cell death. The rates and extents of cell death were similar for both verotoxin-producing and nonproducing strains of EHEC as well as for a related gastrointestinal pathogen, enteropathogenic E. coli (EPEC). The induction of apoptosis by bacterial attachment was independent of verotoxin production and greater than that produced by a similar treatment with verotoxin alone. Expression of phosphatidylethanolamine, previously reported to bind EHEC and EPEC, was also increased on apoptotic cells but with little correlation to phosphatidylserine expression. Phosphatidylethanolamine levels but not phosphatidylserine levels on dying cells correlated with EHEC binding. Cells treated with phosphatidylethanolamine-containing liposomes also showed increased EHEC binding. These results suggest that bacterial induction of apoptosis offers an advantage for bacterial attachment by augmenting outer leaflet levels of the phosphatidylethanolamine receptor.
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Comparison of Helicobacter mustelae and Helicobacter pylori adhesion to eukaryotic cells in vitro
Gastroenterology, 1995Co-Authors: Benjamin D. Gold, Marlene Dytoc, Mario Huesca, Dana J. Philpott, Steven J Czinn, Arnis Kuksis, Philip M ShermanAbstract:Abstract Background & Aims: Bacterial adhesion to mucosal surfaces is an important pathogenic mechanism for Helicobacter -induced gastritis. The aims of this study were to compare binding of selected Helicobacter mustelae and Helicobacter pylori strains to lipids extracted from HEp-2, Chinese hamster ovary, human embryonic lung cells, and ferret gastrointestinal tissues as well as to intact tissue culture cells and to analyze the fatty acids of the receptor. Methods: Thin-layer chromatography overlay binding and a receptor-based immunoassay detected adhesion of bacteria to commercial lipids and to individual species within the lipid extracts. H. mustelae binding to tissue culture cells was performed by whole cell bacterial adhesion assay. Results: H. mustelae and H. pylori both bound to phosphatidylethanolamine and lysophosphatidylethanolamine. Adhesion of H. mustelae to intact eukaryotic cells correlated with the amount of phosphatidylethanolamine. Binding of helicobacters was greater to lipids derived from ferret antrum compared with colon ( P Helicobacter binding. Conclusions: Adhesion of Helicobacter strains correlates with the quantity of phosphatidylethanolamine present in the epithelial cell and with the differences in the fatty acid profile of the lipid.
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the glycerolipid receptor for helicobacter pylori and exoenzyme s is phosphatidylethanolamine
Infection and Immunity, 1992Co-Authors: Clifford A Lingwood, Mario Huesca, Arnis KuksisAbstract:Abstract We have previously shown that Helicobacter pylori specifically binds to a glycerolipid species preferentially found in the antrum of the human stomach. We now show by high-pressure liquid chromatographic analysis that this species is a form of phosphatidylethanolamine and that H. pylori specifically binds to bona fide phosphatidylethanolamine as detected by a thin-layer chromatogram overlay procedure. Considerable variation in the binding of H. pylori to phosphatidylethanolamine from different sources was observed, however, suggesting the importance of the nature of the long-chain hydrophobic moiety. A similar binding specificity was shown by exoenzyme S from Pseudomonas aeruginosa, consistent with our hypothesis that that an exoenzyme S-like adhesin is responsible for the binding of H. pylori to its lipid receptors.
Arnis Kuksis - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Helicobacter mustelae and Helicobacter pylori adhesion to eukaryotic cells in vitro
Gastroenterology, 1995Co-Authors: Benjamin D. Gold, Marlene Dytoc, Mario Huesca, Dana J. Philpott, Steven J Czinn, Arnis Kuksis, Philip M ShermanAbstract:Abstract Background & Aims: Bacterial adhesion to mucosal surfaces is an important pathogenic mechanism for Helicobacter -induced gastritis. The aims of this study were to compare binding of selected Helicobacter mustelae and Helicobacter pylori strains to lipids extracted from HEp-2, Chinese hamster ovary, human embryonic lung cells, and ferret gastrointestinal tissues as well as to intact tissue culture cells and to analyze the fatty acids of the receptor. Methods: Thin-layer chromatography overlay binding and a receptor-based immunoassay detected adhesion of bacteria to commercial lipids and to individual species within the lipid extracts. H. mustelae binding to tissue culture cells was performed by whole cell bacterial adhesion assay. Results: H. mustelae and H. pylori both bound to phosphatidylethanolamine and lysophosphatidylethanolamine. Adhesion of H. mustelae to intact eukaryotic cells correlated with the amount of phosphatidylethanolamine. Binding of helicobacters was greater to lipids derived from ferret antrum compared with colon ( P Helicobacter binding. Conclusions: Adhesion of Helicobacter strains correlates with the quantity of phosphatidylethanolamine present in the epithelial cell and with the differences in the fatty acid profile of the lipid.
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the glycerolipid receptor for helicobacter pylori and exoenzyme s is phosphatidylethanolamine
Infection and Immunity, 1992Co-Authors: Clifford A Lingwood, Mario Huesca, Arnis KuksisAbstract:Abstract We have previously shown that Helicobacter pylori specifically binds to a glycerolipid species preferentially found in the antrum of the human stomach. We now show by high-pressure liquid chromatographic analysis that this species is a form of phosphatidylethanolamine and that H. pylori specifically binds to bona fide phosphatidylethanolamine as detected by a thin-layer chromatogram overlay procedure. Considerable variation in the binding of H. pylori to phosphatidylethanolamine from different sources was observed, however, suggesting the importance of the nature of the long-chain hydrophobic moiety. A similar binding specificity was shown by exoenzyme S from Pseudomonas aeruginosa, consistent with our hypothesis that that an exoenzyme S-like adhesin is responsible for the binding of H. pylori to its lipid receptors.
Sean S Davies - One of the best experts on this subject based on the ideXlab platform.
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Dietary Fatty Acids Control the Species of N‑Acyl-Phosphatidylethanolamines Synthesized by Therapeutically Modified Bacteria in the Intestinal Tract
2017Co-Authors: Noura S. Dosoky, Zhongyi Chen, Lilu Guo, Andrew V. Feigley, Sean S DaviesAbstract:Engineering the gut microbiota to produce specific beneficial metabolites represents an important new potential strategy for treating chronic diseases. Our previous studies with bacteria engineered to produce N-acyl-Phosphatidylethanolamines (NAPEs), the immediate precursors of the lipid satiety factors N-acyl-ethanolamides (NAEs), found that colonization of these bacteria inhibited development of obesity in C57BL/6J mice fed a high fat diet. Individual NAE species differ in their bioactivities. Intriguingly, colonization by our engineered bacteria resulted in increased hepatic N-stearoyl-ethanolamide (C18:0NAE) levels despite the apparent inability of these bacteria to biosynthesize its precursor N-stearoyl-phosphatidylethanolamine (C18:0NAPE) in vitro. We therefore sought to identify the factors that allowed C18:0NAPE biosynthesis by the engineered bacteria after colonization of the intestinal tract. We found that the species of NAPE biosynthesized by engineered bacteria depends on the species of dietary fatty acids available in the intestine, suggesting a simple method to fine-tune the therapeutic effects of modified microbiota
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isolevuglandin modified phosphatidylethanolamine is metabolized by nape hydrolyzing phospholipase d
Journal of Lipid Research, 2013Co-Authors: Stephen Gragg, Zhongyi Chen, Venkataraman Amarnath, Yongqin Zhang, Sean S DaviesAbstract:Oxidative stress has been implicated in atherosclerosis, diabetes, neurodegenerative diseases, and various cancers. Peroxidation of lipids generates a number of highly reactive aldehydes including isolevuglandins (IsoLGs) (1, 2). IsoLGs induce a variety of cellular responses related to the pathophysiology of human diseases, including increased macrophage uptake of LDL, activation of platelet aggregation, inhibition of sodium and potassium channels, inhibition of proteasome function, induction of proinflammatory genes, and cytotoxicity (3–6). Recent studies show that the proinflammatory and cytotoxic effects of lipid aldehydes such as IsoLGs are mediated in part by their modification of the headgroups of Phosphatidylethanolamines (PEs) (7–9). Isolevuglandin-modified phosphatidylethanolamine (IsoLG-PE) levels increase during a number of pathological conditions (10–12), suggesting that cellular systems that normally degrade IsoLG-PE may become dysfunctional during these conditions. We therefore sought to characterize the processes by which cells normally degrade IsoLG-PE. N-acyl phosphatidylethanolamine hydrolyzing phospholipase D (NAPE-PLD) catalyzes the hydrolysis of N-acyl Phosphatidylethanolamines (NAPEs) to N-acyl ethanolamines (NAEs) such as anandamide (13). Although both NAPE-PLD and cannonical phospholipase Ds (PLDs) (PLD1 and PLD2) hydrolyze the headgroups at the phosphodiester bond of phospholipids, these two classes of PLDs do not share structural or enzymatic homology. Unlike the canonical PLDs, NAPE-PLD does not transphosphatidylate phospholipids, nor does it hydrolyze phosphatidylcholine (PC) or unmodified PE (14–16). Instead, NAPE-PLD hydrolyzes NAPE with N-acyl chains of 4 to 20 carbons, with C12:0NAPE having the highest hydrolysis rate (15). While NAPE-PLD−/− mice have significantly increased levels of NAPE and reduced levels of NAEs such as oleoylethanolamide and palmitoylethanolamide compared with wild-type mice, anandamide levels are not changed in NAPE-PLD−/− mice (17), raising the possibility that the main physiological role of NAPE-PLD may be something other than endocannabinoid synthesis. Because both NAPE and IsoLG-PE have large aliphatic headgroups, we considered the possibility that NAPE-PLD is a critical catabolic enzyme for the catabolism of IsoLG-PE and other aldehyde-modified PEs (al-PEs). Our studies demonstrate that NAPE-PLD does indeed hydrolyze IsoLG-PE.
D R Voelker - One of the best experts on this subject based on the ideXlab platform.
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cloning and expression of a novel phosphatidylethanolamine n methyltransferase a specific biochemical and cytological marker for a unique membrane fraction in rat liver
Journal of Biological Chemistry, 1993Co-Authors: Zheng Cui, Jean E. Vance, M H Chen, D R VoelkerAbstract:Phosphatidylethanolamine N-methyltransferase catalyzes the synthesis of phosphatidylcholine from phosphatidylethanolamine and is most active in liver. A cDNA for this enzyme from a rat liver cDNA library has been cloned, sequenced, and expressed in COS-1 cells, McArdle-RH7777 rat hepatoma cells, and Sf9 insect cells. The expressed protein was capable of converting phosphatidylethanolamine into phosphatidylcholine in intact COS-1 cells, which normally have very low methyltransferase activity. The calculated molecular mass of the methyltransferase protein is 22.3 kDa, which is equivalent to that of the pure protein isolated from rat liver. Comparison of the sequence of the cloned rat liver methyltransferase with the yeast phosphatidylethanolamine methyltransferase PEM2 gene product revealed 44% identical amino acids and 68% similarity in the two predicted protein sequences. A polyclonal antibody was raised against a synthetic peptide corresponding to the carboxyl-terminal region of the enzyme and was affinity purified. The antibody recognized a single protein with a molecular mass of approximately 20 kDa when either rat liver proteins or proteins derived from the transfected COS-1 cells were electrophoresed on polyacrylamide gels containing sodium dodecyl sulfate. Surprisingly, the antibody exhibited no reactivity with endoplasmic reticulum proteins, even though the major phosphatidylethanolamine methyltransferase activity resides on this subcellular organelle. Instead, the antibody specifically recognized a protein in a unique subcellular membrane fraction purified from a crude mitochondrial preparation on a Percoll gradient. Immunocytochemical examination by electron microscopy showed positive labeling only in unique regions of the hepatocytes. The data suggest that this phosphatidylethanolamine methyltransferase is a specific marker for this unique membrane fraction.
Luis B Agellon - One of the best experts on this subject based on the ideXlab platform.
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biochemical and evolutionary significance of phospholipid methylation
Journal of Biological Chemistry, 1998Co-Authors: Christopher J. Walkey, Liqing Yu, Luis B AgellonAbstract:Abstract All nucleated mammalian cells synthesize phosphatidylcholine from choline via the CDP-choline pathway. Hepatocytes have a second pathway for the synthesis of phosphatidylcholine, a stepwise methylation of phosphatidylethanolamine, catalyzed by phosphatidylethanolamineN-methyltransferase and encoded by the Pemptgene. We report that when Pempt-deficient mice were fed a choline-deficient diet for 3 days, severe liver pathology occurred apparently due to a lack of phosphatidylcholine biosynthesis. The hepatic concentration of phosphatidylcholine decreased by 50% compared with wild type mice on the diet. The levels of plasma triacylglycerols and cholesterol were decreased by greater than 90% in thePempt-deficient mice. We suggest that the Pemptgene has been maintained during evolution to provide phosphatidylcholine when dietary choline is insufficient, as might occur during starvation or pregnancy.